Pulsed Vector Atomic Magnetometer Using an Alternating Fast-Rotating Field

TL;DR

This paper presents a novel pulsed vector atomic magnetometer that uses a fast-rotating magnetic field to measure magnetic field magnitude and direction simultaneously with high sensitivity and resolution, overcoming common systematic challenges.

Contribution

The authors introduce a new method employing a fast-rotating magnetic field in a pulsed scalar magnetometer to enable vector measurements with high sensitivity and systematic error mitigation.

Findings

Achieved a total field gradient sensitivity of 35 fT/√Hz.

Realized angular resolutions of 6 nrad/√Hz at 50 μT.

Noise spectra remain flat down to 1 Hz and 0.1 Hz.

Abstract

We introduce a vector atomic magnetometer that employs a fast-rotating magnetic field applied to a pulsed $^{87}$Rb scalar atomic magnetometer. This approach enables simultaneous measurements of the total magnetic field and its two polar angles relative to the rotation plane. Operating in gradiometer mode, the magnetometer achieves a total field gradient sensitivity of 35 $\mathrm{fT/\sqrt{Hz}}$ (0.7 parts per billion) and angular resolutions of 6 $\mathrm{nrad/\sqrt{Hz}}$ at a 50 $\mu$T Earth field strength. The noise spectra remain flat down to 1 Hz and 0.1 Hz, respectively. Here we show that this method overcomes several metrological challenges commonly faced by vector magnetometers and gradiometers. We propose a unique peak-altering modulation technique to mitigate systematic effects, including a newly identified dynamic heading error. Additionally, we establish the fundamental sensitivity limits of the sensor, demonstrating that its vector sensitivity approaches scalar sensitivity while preserving the inherent accuracy and calibration benefits of scalar sensors. This high-dynamic-range, ultrahigh-resolution magnetometer offers exceptional versatility for diverse applications.